DIY Home Improvement, Remodeling & Repair Forum > DIY Home Improvement > Electrical and Wiring > One switch controls 2 lights




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Old 04-09-2014, 09:44 PM  
Mattr
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The wiring diagram I am speaking of is the smaller of the two pictures on post #4, using 3 wire between Light fixtures.


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Old 04-09-2014, 09:58 PM  
nealtw
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Take one wire off the switch, do the lights go off? Test the switch, does the switch open?


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Old 04-10-2014, 06:53 AM  
JoeD
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Connect the fixture and see what happens. It will either be on or off all the time or work properly. You will not cause and harm.

If you are using a digital meter you could be getting a false reading called phantom voltage.
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Old 04-10-2014, 08:33 AM  
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Connect the fixture and see what happens. It will either be on or off all the time or work properly. You will not cause and harm.

If you are using a digital meter you could be getting a false reading called phantom voltage.
In post 10 he did that and the lights stayed on.
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Old 04-10-2014, 08:54 AM  
Wuzzat?
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For one switch controlling two lights the basic circuit is that
the lights are in parallel (assembly 1),
the switch and the power source are in series (assembly 2),
and these two assemblies are in series.

In addition, the lamp socket center contact should be hot (120v above ground) so that the threaded shell which is more accessible to the user is close to ground.

What gets messy is having the additional constraint of having the wire colors correspond to some version of the electrical code so future workers know what you did.
Houses don't seem to come with schematics or wiring diagrams; the wire colors are the diagram.

For further confusion: are outlets in a branch circuit in series or in parallel?
I'd say the hot sides (short slots) are in series and
the neutral sides (long slots) are in series but
each outlet is in parallel with the others.

Last edited by Wuzzat?; 04-10-2014 at 09:36 AM.
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Old 04-10-2014, 11:18 AM  
Mattr
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just took off one wire from the switch and i have juice on both sides, so i determined that the switch is bad. Replaced it and we are good. Thanks Nealtw for pointing that out...
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Old 04-10-2014, 11:45 AM  
nealtw
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That is what I was hoping for but I was afraid you had bigger things happening.
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Old 04-10-2014, 11:58 AM  
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Quote:
Originally Posted by nealtw View Post
That is what I was hoping for but I was afraid you had bigger things happening.
And the OP might well have. . . This was lucky.

A wire coming out of a wall could go to hot, neutral, ground, the upstream or downstream side of a switch or a load like a lamp or an appliance or to nothing at all and so you'd get a phantom voltage.
Checking for each can be tedious, especially when your tester gives you false readings.

If I had only one tester it'd be a high wattage 240v bulb or two 120v bulbs in series. A single 120v bulb will do but you run the risk of putting it across 240v. Which reminds me, wear eye protection and if you are really risk-averse, wear face protection.

Last edited by Wuzzat?; 04-10-2014 at 12:02 PM.
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Old 04-10-2014, 12:15 PM  
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Originally Posted by Wuzzat? View Post
And the OP might well have. . . This was lucky.

A wire coming out of a wall could go to hot, neutral, ground, the upstream or downstream side of a switch or a load like a lamp or an appliance or to nothing at all and so you'd get a phantom voltage.
Checking for each can be tedious, especially when your tester gives you false readings.

If I had only one tester it'd be a high wattage 240v bulb or two 120v bulbs in series. A single 120v bulb will do but you run the risk of putting it across 240v. Which reminds me, wear eye protection and if you are really risk-averse, wear face protection.
Let's not go to panic mode to fast. He said, he understude the diagram and followed correctly, that only left the switch. I would not have suggested hooking up the lights in case he had a 220 situation but more likely a mistake would have been 2 sources from the same breaker.
Sometimes the best answer is nothing better than better questions.
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Old 04-10-2014, 01:15 PM  
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Quote:
Originally Posted by nealtw View Post
Let's not go to panic mode to fast. He said, he understude the diagram and followed correctly, that only left the switch. I would not have suggested hooking up the lights in case he had a 220 situation but more likely a mistake would have been 2 sources from the same breaker.
Sometimes the best answer is nothing better than better questions.
One time I figured out how many ways you could hook one, two or three wires to an outlet that has hot, neutral and ground.
Just listing them was exhaustive and amounted to about 30 ways, which means your odds of getting it right by guessing was about 1 in 30.
Of course, DIYers know stuff (some right and some wrong) and so the odds are considerably better but still in favor of Murphy's Law.

IIRC a book on troubleshooting said to take one guess and then get back to basics and follow the tried and true troubleshooting routines, tedious and slow as they may be.
http://www.google.com/search?client=...UTF-8&oe=UTF-8
You trade slowness for certainty.

My guesses, and those of people on forums who fix by replacing parts, are hardly ever right so almost immediately I start checking the basics.
It follows from this that learning the basics will almost always serve you, sooner or later. And knowing these means you hardly ever panic.

A few times I ran into 'impossible' situations, which I soon learned meant that I was assuming something that was not true. Finding that unconscious assumption of mine was real work.



Last edited by Wuzzat?; 04-10-2014 at 01:23 PM.
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